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5150 Power Supply with more watts than the original

S

stangman517

Experienced Member
Joined
Dec 15, 2014
Messages
243
Location
Georgia, USA
Greetings!

Looking for a PS at least 110+ watts and not the 63.5 watts that came with the 5150. I have read these are not good for 5150s with HDDs because IBM originally did not intend HDDs to be in the 5150s with the 63.5 power supply. If this is wrong please let me know.

I'm a 5150 newby, so please excuse lack of knowledge.

Part number I prefer but not essential; just one that's healthy. ;-)

System Unit -Interior (5150)
8529155 Power Supply, 120 Volt

Thanks

* * * Update Update ***
I found one. Thanks all.
 
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It depends on the hard drive in reality, there are quite a few of us whom have run a hard-card in a 5150 on a 63.5 watt supply with no issues. I personally have gotten one to take a full height hard drive, with one floppy drive, and no extra boards. I was not about to push the little thing, but it will work. Mileage will vary however.
 
At the time that IBM designed the 5150, hard drives consumed lots of power (relatively speaking). The drive's spindle motor is the main culprit. The diagram at [here] shows the issue. From that, we know that IBM did not intend (at design time) for the IBM 5150 to have a hard drive (well, one powered from the 5150's 63W power supply).

Early hard drives added to the 5150 were self-powered. An example is [here].

But things changed. Later drives, generally speaking, consume less power. Less power can result from fewer platters, platters that are smaller in diameter (e.g. 3.5" form factor versus 5.25" form factor), and more efficient circuitry.

It really comes down to the make/model of drive to be added, and what the existing load is on the power supply. Some people have added drives to an IBM 5150 (that has the original 63W power supply) and it has worked.
 
Hmm that's interesting. I've seen a few higher wattage power supplies on Ebay that are 150w and 192w but WOW are they proud of those guys!

I've got the ST-225, 2 floppies, a RAM card on the way. Do you think this would tax the little fella (63.5w PS)?

Thanks!
 
Interesting pics.

Yeah it's not like I'll be on my 5150 eight hours a day; just working to get a good working/complete system. Wow things are starting to get expensive!

Thanks modem7.
 
stangman517 said:
I've got the ST-225, 2 floppies, a RAM card on the way. Do you think this would tax the little fella (63.5w PS)?
Click to expand...
A power rating breakdown of the IBM 63W power supply is shown at [here].
The +5V and +12V are the important ones.
So, the IBM 63W power supply is power rated for 35W of +5V, and 24W of +12V.

In theory, by knowing the power requirements of each device in your 5150, you can work out whether or not there is going to be a problem.
For example, I show the approximate power requirements of certain devices at [here].

But in doing calculations, it is not simply a matter of adding up all of the PEAK values for your devices. That is because sometimes the peaks occur at different times, per the diagram at [here]. And a complication is that some power supplies can tolerate very short periods of overload (before overload protection activates). Maybe the IBM 63W power supply can do that (but maybe not).

On the +12V line, the startup power requirement of a hard drive (a traditional rotating platter type) will be the most significant demand. Specs for the ST-225 drive indicate a +12V startup power requirement of 28W. 28W exceeds the 24W of rated +12V power of the IBM 63W power supply, however, various things are in play (possible temporary overload tolerance, safety margin in the power supply, ...)

Try the ST-225 (in addition to everything else) and see what happens.
 
You can also just swap the innards of the PSU with those from a later third-party AT PSU. Did that with one of my 5150's as well. See here: http://retro-net.de/48.html (text is in German, but the picture should give you an idea)
 
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